Diagnosis and treatment of bipolar disorder has long been a neglected discipline. Recent years have shown an upsurge in bipolar research. When compared to major depressive disorder, bipolar research still remains limited and more expert based than evidence based. In bipolar diagnosis the focus is shifting from classic mania to bipolar depression and hypomania. There is a search for bipolar signatures in symptoms and course of major depressive episodes. The criteria for hypomania are softened, leading to a bipolar prevalence that now equals that of major depressive disorder. Anti-epileptics and atypical antipsychotics have joined lithium in the treatment of bipolar disorder. Fortunately, mood stabilization has become the core issue in bipolar disorder treatment. In contrast with recent trends in the diagnosis of bipolar disorder, treatment research remains more focused on classic mania than depression or hypomania. This leaves the clinician with the difficult task of diagnosing 'new bipolar patients' for whom no definite evidence-based treatment is available. An important efficacy-effectiveness gap further compromises the translation of the evidence base on bipolar disorder treatment into clinical practice. The recent upsurge of research on bipolar disorder is to be applauded, but further research is needed: for bipolar disorder in general, and for bipolar depression and the long-term treatment specifically. Given the complexity of the disorder and the many clinical uncertainties, effectiveness studies should be installed.